This invention relates to a centrifugal pump and more particularly to a bearing arrangement for a type of centrifugal pump known as a "sealless pump".
A sealless pump is the type of centrifugal pump that has its impeller and bearing system isolated from the impeller driving mechanism by an isolating wall that seals the pumping mechanism from the surrounding environment and eliminates the necessity to use rotary seals to seal the pumped fluid against leaking along the shaft. This type of pump is particularly desirable when pumping corrosive or toxic fluids which are dangerous when allowed to leak. The driving mechanism is coupled to the pump impeller by an arrangement of magnets located on the opposite sides of the isolating wall which magnetically connects the torque of the driving mechanism to the impeller.
A sealless centrifugal pump must include an impeller bearing system which is independent of the motor driving bearings and therefore necessitates that the impeller bearing system carry the full load on the impeller including both radial and thrust forces. In the past, a designer of this type of pump generally used a closed impeller to reduce the thrust load on the bearing system to a manageable load. However, the use of a closed impeller is undesirable when pumping fluids contaminated with debris or other solid materials because the impeller is more easily clogged and is more difficult to clean than an open impeller.